Method for preparing a mixture of saccharides

ABSTRACT

A method for preparing a mixture of fructose, glucose and compounds of the general formula GF n , wherein G is glucose and F is fructose and n is an integer. The mixture is recovered from plant tubers or roots by means of a method which does not involve any chemical modification of the components of the mixture. A juice or syrup comprising fructose, glucose, sucrose and oligosaccharides is subjected at one or more suitable steps to a physical separation process to reduce the amount of fructose, glucose and sucrose. The physical separation may be carried out by chromatography or nanofiltration or both. The mixture is suitable for use in foodstuffs and beverages for human beings and animals.

TECHNICAL FIELD

The present invention relates to a method for preparing a mixture offructose, glucose and compounds of the general formula GF_(n), wherein Gis glucose and F is fructose and n is an integer, where the mixture isrecovered from plant tubers or roots by means of a method which does notinvolve any chemical modification of the components of the mixture.Furthermore, the present invention relates to the use of such a mixturefor preparing a low-calorie foodstuff or beverage for animals or humanbeings.

BACKGROUND ART

The method according to the present invention is a development of themethod disclosed in Danish patent application No. 1592/88, filed 23 Mar.1988, and the corresponding PCT-application No. PCT/DK89/00065 (WO89/09288), and relating to a method for preparing a mixture of fructose,glucose and compounds of the general formula GF_(n), wherein G isglucose and F is fructose and n is an integer, said mixture comprisingcalculated as dry matter 10-20% by weight of G+F+GF, 10-20% by weight ofGF₂, 8-15% by weight of GF₃, and 72-45% by weight of GF₄ and above byrecovering said mixture from plant tubers or roots by means of a methodwhich does not involve any chemical modification of the components ofthe mixture.

The mixture prepared according to DK patent application No. 1592/88 isuseful as a low-calorie material with sweet taste.

Sucrose has heretofore been widely used in confectionary and food byvirtue of its excellent characteristics, such as good sweetness, body,taste and crystallinity. Sucrose, however, constitutes a substrate fordextransucrase produced by intraoral microorganisms, and, as a result,consecutive intake of sucrose leads to formation of large amounts ofinsoluble dextran in the mouth. Thereby formation of dental plaque isaccelerated. Therefore, sucrose is said to possess cariogenicity.Recently, there has been a trend to reduce the calorie intake forprevention of obesity and a low-calorie sweet material, instead of ahigh-calorie one, such as sucrose, has been demanded.

For this reason many suggestions have been made as to find a sweetmaterial for replacing sucrose, such as the artifical sweetenerssaccharin, cyclamate, aspartame, sorbitol and many others.

Such alternative sweeteners are widely used but also possess severaldisadvantages, such as a bitter tang or aftertaste. Furthermore, some ofthe artificial sweeteners are suspected to be carcinogenic.

These disadvantages, especially the suspicion of being carcinogenic--arecurrent subject in the public debate--have made consumers reluctant touse products containing any type of artificial sweetener.

It is known that the dahlia tubers contain a polysaccharide known asinulin. According to Merck Index, 10th edition, Merck & Co. Inc.,Rahway, N.J., U S A, 1983, p. 725, Index No. 4872, it has the formulaGF_(n) with n being of an average value of approx. 37. The preparationof inulin from dahlia tubers is disclosed in U.S. Pat. No. 4,285,735.

It is also known that chicory roots and Jerusalem artichoke tuberscontain corresponding polysaccharides or oligosaccharides with thegeneral formula GF_(n). The value of n varies depending on the raw plantmaterial in question, cf. e.g. S. E. Fleming et al. Preparation ofhigh-fructose syrup from the tuber of the Jerusalem artichoke(Helianthus tuberosus L.), CRC Crit. Rev. Food Sci. Nutr., 11, 1-23,1979, U.S. Pat. No. 4,613,377 and EP patent application No. 0 201676/A2.

The interest in these polysaccharides and oligosaccharides in form ofinulin or inulin-like compounds (inulides) has until now been directedto the large contents of fructose moities in said compounds. They arethus a useful source for the preparation of fructose, especially withregard to using fructose as nutrient replenisher and sweetener.

EP patent application 0 201 676 discloses a method for preparing alow-glucose cleavage product from plant parts, said cleavage productcomprising inulin-like oligo- or polysaccharides. According to thismethod the extracted oligo- or polysaccharides are subjected totreatment with the enzyme inulinase in order to decompose them tofructose and fructose-oligomers.

U.S. Pat. No. 4,613,377 discloses a method where the inulin-likeoligosaccharides obtained from Jerusalem artichoke tubers or chicoryroots are subjected to partial or substantially complete hydrolysis.

Further prior art disclosing the general state of the art comprises thefollowing.

GB patent No. 1,405,987 discloses the preparation of a mixture offructose and glucose, i.e. invert sugar, by crystallization.

U.S. Pat. No. 2,555,386 discloses the preparation of inulin fromJerusalem artichoke. The inulin obtained is used as a substitute forstarch and for the preparation of levulose and alcohol.

U.S. Pat. No. 4,138,272 discloses a method for the preparation offructose from xerophyte plants, for example agave.

DE Offenlegungsschrift No. 3,211,776 discloses a method for obtainingjuice from Jerusalem artichoke to be used for the preparation ofhydrocarbons, for example acetone butanol.

Derwent's abstract No. 87-305.414/43, SU patent application No. 306,061(SU patent No. 1,300,032) discloses the preparation of fructose fromJerusalem artichoke.

Non-patent literature concerning the analyses of "inulin" from Jerusalemartichoke is mentioned in

Chemical Abstracts (CA), vol. 26, (1932), p. 5355, Food Ind. 4,66-9(1932);

CA, vol. 29, (1935), p. 8387, Sovet. Sakhar 1935, No. 1, 4-47;

CA, vol. 50, ( 1956), col. 13152 g, Trudy Komissii Anal. Khim., Akad.Nauk. S.S.S.R., Inst. Geokhim. i Anal. Khim. 6, 492-7(1955);

CA, vol. 51, (1957), col. 9813 a, Zucker-Beih. 3, 86-94(1957);

CA, col 53, (1959), col. 18189 c, Cukoripar 12, 126-9(1959).

GB patent applications Nos. 2,072,679, 2,105,338 and 2,179,946 disclosea low-calorie sweet material comprising a mixture of oligosaccharideswith 1-4 molecules fructose bound to sucrose, i.e. a mixture of theoligosaccharides GF₂, GF₃, GF₄ and GF₅. The above mixture is prepared bystepwise synthesis from sucrose letting the enzyme fructosyl transferaseact upon sucrosa: ##STR1##

This synthesis is expensive and yields only small amounts of theoligosaccharides GF₄ and GF₅. Moreover, the above reaction 1) results inthe production of an excess of glucose. The known sweet material isavailable under the name "Neosugar", both in form of a syrup and apowder. "Neosugar" does not possess the detrimental effects of sucroseor alternative artificial sweeteners mentioned above. Its preparationis, however, too expensive to allow wide use thereof. Furthermore,consumers are probably reluctant to use the product if presented as achemically modified product.

Prior to DK patent application No. 1592/88 there was thus a need for amethod allowing the preparation of a sweetener on the basis of a naturalmixture without the detrimental effects of sucrose and conventionalalternative sweeteners, said method being inexpensive and not involvingchemical modification of the desired natural components in the startingmaterials.

It was shown that a material in form of a mixture of saccharidessatisfying these needs could be prepared from a natural raw material,i.e. plant tubers or roots, e.g. tubers of the Jerusalem artichoke,Helianthus tuberosus L. or roots of chicory, Cichorium.

Accordingly DK patent application No. 1592/88 discloses a method forpreparing a mixture of fructose, glucose and compounds of the generalformula GF_(n), wherein G is glucose and F is fructose and n is aninteger, said mixture comprising calculated as dry matter 10-20% byweight of G+F+GF, 10-20% by weight of GF₂, 8-15% by weight of GF₃, and72-45% by weight of GF₄ and above by recovering said mixture from planttubers or roots by means of a method which does not involve any chemicalmodification of the components of the mixture.

By using the above method it is possible to prepare the mixture ofsaccharides in form of a dry powder at a price of less than half thecosts involved in the preparation of the mixture known from GB patentapplication No. 2,072,679 according to the methods disclosed in GBpatent applications Nos. 2,072,679, 2,105,338 and 2,179,946.

The composition of the mixture prepared by the above method differs fromthe composition of inulin derived from dahlia tubers by having a lowerdegree of polymerisation. Thus the ratio F/G is 3-4 for the above ascompared to inulin where the ratio F/G is approx. 30.

An essential requirement for any material used as sweet material is itswater-solubility. The above mixture has a composition or degree ofpolymerisation within such limits that, on the one hand, theconstituents are sufficiently large to pass predominantly undigestedthrough the alimentary tract. On the other hand, the constituents arestill water-soluble. The inulide mixture obtained from dahlia tubers isnot soluble in water in its unmodified form, and has thus to besubjected to chemical or other modification, such as hydrolysis, if awater-soluble product is desired.

The mixture prepared according to the above method has a goodcombination of sweetening effect, water solubility and indigestibility.However, when the sweetening effect is of minor importance and/or anespecially low calorie content is desired it would be desirable toreduce the content of fructose, glucose and sucrose.

The method according to DK patent application No. 1592/88 is describedin greater detail below.

The mixture is obtained from plant tubers or roots, preferably tubers,of Jerusalem artichoke (Helianthus tuberosus L.) or roots of chicorybecause these plants give a high yield of the mixture of the mentionedcomposition. When the Jerusalem artichoke is cultivated in a temperateclimate the tubers harvested during the major part of the harvestingseason result in a mixture of a almost constant composition.

The mixture is advantageously prepared in form of a dry powder, thusenabling an easier handling and a more stable product. It is, however,also possible to use the mixture in form of a juice or syrup, especiallyfor industrial use, when shipment in large amounts, e.g. in a tank,directly to the user is possible and convenient. In this case theproblems in connection with the removal of the remaining water areavoided.

The mixture can be prepared from Jerusalem artichoke tubers or roots ofchicory by first preparing a syrup, i.e. a concentrated solution with adry matter content of between 65 and 80% by weight. The syrup is thenevaporated further and dried until the desired powdery product isobtained.

Syrup from Jerusalem artichoke tubers or roots of chicory can beprepared in a manner resembling conventionally used methods for thepreparation of sucrose syrup from sugar beets. It is thus possible toperform this part of the production with a conventional sugar beetplant. This is advantageous in that the capacity of existing plants isconsiderably larger than is demanded on the world market. It is thuspossible to use this free capacity for the preparation of the inulidemixture.

Syrup from Jerusalem artichoke tubers or roots of chicory is prepared asfollows. Stones, green parts and soil are removed from Jerusalemartichoke tubers or roots of chicory and the tubers or roots are cutinto cosettes. These are extracted with water in a so-calledDDS-diffusor, i.e. a trough with a steam mantle. The trough has a smallinclination and is provided with a twin screw for the transport of thecosettes counter to the flow of water. The extraction is performed at60°-85° C. and the desired mixture is transferred to water in dissolvedform. Part of the protein content is denaturated, thus rendering itinsoluble. Enzymes present in the solution are also denaturated and thusinactivated so that they cannot decompose the desired mixture. Theaqueous extract has a dry matter content of 10-17% by weight.

Impurities, such as pectin, proteins and cell material, are removed fromthe extract by adding slaked lime, Ca(OH)₂, up to a pH-value of10.5-11.5. After adding the slaked lime the following alternatives areopen:

1. filtration followed by adjusting the pH value by adding CO₂ orphosphoric acid and subsequent filtration, or

2. adding CO₂ or phosphoric acid and subsequent filtration, i.e. theextract is only filtered once.

In a further embodiment the extract is treated with slaked lime in twosteps, i.e. it is subjected to a pretreatment and to a main treatmentwith slaked lime. Then CO₂ is added followed by filtration. Then CO₂ isadded again followed by filtration. The above filtration steps can ofcourse also be carried out by technically equivalent separation methods.

Salts and colours may be removed by means of ion exchange. Residues ofcolours and undesired taste and odoriferous compounds may be removed bysubsequent treatment with active carbon.

The purified extract with a dry matter content of 8-14% by weight can besubjected to hyperfiltration (reverse osmosis) in order to remove waterup to a dry matter content of approx. 25-30% by weight. In a multi-stepevaporator, such as a falling film evaporator, the extract issubsequently concentrated to a syrup with a dry matter content of 75-85%by weight.

This syrup is further evaporated to a dry matter content of 91-96% byweight by means of evaporation e.g. in a vertical vacuum dryer or a thinfilm evaporator.

On the basis of such a syrup the mixture is prepared in form of a drypowder by using one of two alternative methods, i.e. one termed "dryingwith quenching" and one termed "vacuum flash drying". These methods aregenerally suitable for the concentration of syrup-like materials, andare subject matter of the DK patent applications Nos. 1593/88 and1594/88, respectively, both filed 23 Mar. 1988.

It is thus possible to prepare the above inulide mixture in form of adry powder. Such a dry powder is bacteriologically stable. High osmoticpressure is required for obtaining bacteriological stability. For therelatively high molecular weight oligosaccharides a high osmoticpressure is first obtained at a high dry matter content.

A liquid mixture with a sufficiently high dry matter content isdifficult to handle in the preparation step as well as during theapplication of said mixture, as it has an almost paste-like consistencyresembling soft toffee mass. Consequently such a mixture flows veryslowly without solidifying and is very sticky. As mentioned above,however, it is possible to use the mixture in form of a juice or syrupif the above problems are of no importance, e.g. in case of industrialuse in large amounts.

The dry mixture obtained by one of the methods disclosed in DK patentapplications Nos. 1593/88 and 1594/88 can successfully be used as apartial or complete substitute for sugar and other sweet materialsincluding sorbitol.

The method for the preparation of the mixture in form of a dry powdercomprises carrying out the following steps:

a) the substantially cleaned tubers or roots are cut into cosettes,

b) the cosettes are subjected to extraction with water,

c) the extract, or juice, is treated in a suitable order one or moretimes by each of the following steps:

1) addition of Ca(OH)₂,

2) addition of CO₂ or phosphoric acid, and

3) filtration,

d) the juice from step c) is subjected to ion exchange,

e) the juice from step d) is optionally treated with active carbon,

f) the juice from step d) or e) is optionally concentrated byhyperfiltration,

g) the juice from step d), e) or f) is evaporated to a syrup with a drymatter content of 91-96% by weight,

h) the syrup is dried to a powder.

For overcoming the difficulties during the evaporation of thehigh-concentrate syrup, step h) is advantageously carried out by one ofthe following methods, i.e. either

i) the syrup is distributed as a thin layer on a cooling surface with atemperature of below 0° C., preferably between minus 10° C. and 0° C.,whereby the syrup solidifies to a hard, glass-like mass,

k) the hard, glass-like mass formed in step i) is scraped off thecooling surface in form of flakes,

1) the flakes are roughly ground and

m) the roughly ground flakes are dried at a temperature of below 60° C.to a dry matter content of above 96% by weight, preferably above 97% byweight, or

n) the temperature of the syrup is adjusted to a value below the boilingpoint of said syrup at atmospheric pressure,

o) the syrup is fed into a vacuum chamber,

p) the syrup is led through the vacuum chamber without any heat supplyto the syrup,

q) the obtained dried or evaporated mixture is removed from the vacuumchamber through an air lock.

If it is possible to use the mixture as a juice, only the above stepsa)-f) is carried out. Then the juice can be evaporated to a syrup ifdesired. In this way the problems connected with removing remainingwater are avoided.

As mentioned before, there is a demand for removing or at least reducingthe content of mono- and disaccharides, in the mixture of inulidesprepared according to DK patent application No. 1592/88. This is due toi.a. the above-mentioned desire to reduce the calorie content andcariogenic effect of lower saccharides, while at the same time retainingthe preferred inulides. Accordingly, the inulide compounds of formulaGF₂ and above are especially desirable. Such compounds are beneficial toones health, since, like fibers, they pass the alimentary tract withoutbeing digested. In contrast to the result of ingestion of lowersaccharides a violent increase of the glucose level is avoided, thelatter being an important risk factor with diabetes. At the same timethe preferred inulides support the growth of bacteria of the genusBifidobacterium naturally occuring in the intestinal flora. Moreover thepreferred inulides act as bulking agents in foodstuffs. This is ofparticular importance for an attractive texture of the foodstuff inquestion. On the other hand, it can also be desirable to remove higheroligosaccharides, such as GF_(n), n>10, to improve the water-solubilityof the mixture.

DISCLOSURE OF THE INVENTION

The object of the present invention is to solve the problems arisingfrom the method disclosed in DK patent application No. 1592/88.

The object of the invention is accomplished by a method characterized bysubjecting at one or more suitable steps a juice or syrup comprisingfructose, glucose, sucrose and oligosaccharides to a physical separationprocess during one or more suitable steps to reduce the amount offructose, glucose and sucrose.

When carrying out the method according to the invention the resultinginulide mixture has a more suitable composition than the mixtureobtained by the method according to Danish patent application No.1592/88. The inventive method does not involve any chemical modificationof the components of the mixture either, which as mentioned above can beof great importance for the product to be accepted by the consumer.

A further advantage of the inventive method is the removal of saltsduring the physical separation process resulting in a reduction of costsinvolved in ion exchange of the juice during the above step c). Eitherthe volume of the ion exchanger can be reduced or more juice can betreated before the ion exchanger has to be regenerated.

The removal of sucrose, glucose and fructose by the inventive methodallows a reduction of calories, such as from about 2.5 kcal/g to 1.5-2.2kcal/g.

The physical separation also allows a standardization of the mixture,i.e. a uniform composition is ensured regardless of the raw materialchosen or its composition, which can for instance be depended on thetime of harvest. Consequently production cost can be considerablyreduced and a longer production period can be envisaged so that existingapparatuses can be more efficiently used.

According to the present invention it is possible to obtain a mixutrewith a preferred composition comprising calculated as dry matterk

0-10% by weight of G+F+GF,

5-20% by weight of GF₂,

5-15% by weight of GF₃,

5-15% by weight of GF₄,

5-15% by weight of GF₅, and

80-25% by weight of GF₆ and above.

Advantageously the physical separation is carried out by chromatographyor nanofiltration or both. The order in which the steps are carried outis not critical. Thus chromatography or nanofiltration may be used aloneor advantageously in combination in any given order.

According to the invention tubers of Jerusalem artichoke (Helianthustuberosus L.) and roots of chicory (Cichorium) can be used to recoverthe mixture, resulting in a high yield of an advantageous composition.

Depending on the application of the mixture, the latter can be preparedin form of a juice, a syrup or a dry powder.

When carrying out the method according to the invention by

a) cutting the substantially cleaned tubers or roots into cosettes,

b) subjecting the cosettes to extraction with water,

c) treating the extract, or juice, in a suitable order one or more timesby each of the following steps:

1) addition of Ca(OH)₂,

2) addition Of CO₂ or phosphoric acid, and

3) filtration

d) subjecting the juice from step c) to ion exchange,

e) optionally treating the juice from step d) with active carbon,

f) optionally concentrating the juice from step d) or e) byhyperfiltration,

g) optionally evaporating the juice from step d), e) or f) to a syrup,and

h) optionally drying the syrup to a powder,

the physical separation is advantageously carried out during anysuitable moment subsequent to step c) but prior to step h). In case thephysical separation is carried out prior to ion exchange according tostep d) the costs involved with ion exchange can be reduced, since themixture has been partially desalinated by the physical separation.

Advantageously the physical separation may be carried out bychromatography, preferably by chromatography of the juice or syrup usingan ion exchange resin and water as eluant, whereupon the elutedfractions with low sucrose content are treated in accordance with any ofthe subsequent steps. A particular advantage of chromatography is thepossibility of simultaneous removal of or reduction of the amount ofhigher molecular weight compounds, for instance compounds of the formulaGF_(n), where n>10.

In an other advantageous embodiment of the invention the physicalseparation is carried out by nanofiltration, preferably bynanofiltration of a juice or syrup, whereupon the retentate is treatedin accordance with any of the subsequent steps.

In the present specification and claims nanofiltration denotesfiltration with a membrane having a NaCl-permeability of 30-100% at 20°C. and 10-60 bar. The NaCl-permeability is determined by using thefollowing equation: ##EQU1##

Nanofiltration also results in the removal of low molecular weightproteins and amino acids, so that the purity of the inulide mixture isimproved. The discarted fractions containing sucrose and protein aresuitable for animal feed.

The mixture prepared according to the invention is suitable forincorporation in a low-calorie foodstuff or beverage for animal or humanuse. The resulting product is very healthy due to the reduced content oflow saccharides. At the same time the organoleptic properties of suchfoodstuffs are often improved.

As mentioned above, it is not critical when or in which order thephysical separation is carried out. In a preferred embodiment of theinvention the physical separation is carried out after treatment of thejuice with slaked lime and filtration according to step c) and beforethe ion exchange according to step d). In this case the physicalseparation may be performed by nanofiltration alone, by chromatographyalone, by nanofiltration followed by chromatography or by chromatographyfollowed by nanofiltration. All these possibilities result in a reducedcontent of salt, sugar, protein and water. The reduced salt contentagain results in the subsequent ion exchange becoming less expensive.

In a further embodiment the decoloured juice of step e) with or withoutpartial evaporation is subjected to the physical separation. Thisconstitutes either a supplementary or alternative measure. In thisembodiment the physical separation can advantageously be performed bychromatography alone, by ultrafiltration followed by chromatography andby chromatography followed by ultrafiltration.

Chromatography is advantageously carried out on a cation exchange resinin the Na⁺ -, K⁺ -, Ca⁺⁺ or Mg⁺⁺ form, such as a "Duolite™" C204, C207or C211 or a "Dowex™" cation exchange resin. The mixture fed to the ionexchanger can have a dry matter content of 10 to 80% by weight.Chromatography can be carried out at any suitable temperature, forinstance in the range of from 20° to 80° C. Chromatography is performedat a flux velocity of 0.1 to 1 ion exchanger volume/h. The mixture isadded until the ion exchange resin has been charged with 10 to 100 g drymatter per liter. During elution the sucrose content of the fractions ismonitored by means of a refractometer on the output side of thechromatography column.

Nanofiltration is carried out with membranes having a NaCl-permeabilityof 30 to 100% at 20° C. and 10-60 bar. Suitable membranes include HC50PP available from DDS Filtration, DK-4900 Nakskov, and Desal-5 availablefrom Desalination Systems, 1238 Simpson Way, Escondido, Calif. 92025,USA. Nanofiltration can be carried out at 10°-80° C. with a pressure of10-60 bar.

The mixture prepared according to the inventive method is suitable forthe preparation of low-calorie human or animal foodstuffs and beverages.According to the present specification with claims foodstuffs andbeverages include all types of products suitable for human or animalintake, i.e. also pharmaceutical preparations.

Examples for products where the mixture is usable include chewing gum,chocolate, ice cream, liquorice, cakes, all types of biscuits, cannedfood, marmelade and jams, soft drinks, pharmaceutical preparations andvarious other foodstuffs and beverages.

The mixture obtained by the inventive method has a sweetening effect,corresponding to 0.03-0.3 × the one of sucrose, without possessing anytang or aftertaste. Such a sweetening effect being lower than that ofsucrose is advantageously employed in products where a large amount ofsaccharides is desirable with respect to body and texture. Examples ofsuch products include liquorice and certain types of chocolate, wherethe same amount of sucrose would render such products oversweet. Themixture passes the alimentary tract substantially without being digestedthus providing the organism with a very low amount of calories. Themixture also increases the rate with which the food passes thealimentary tract, thus reducing the overall intake of calories. Themixture thus acts as a filler or bulking agent in the alimentary tractin the same way as dietary fibers, i.e. it increases the fecal excretionof sterols and volatile fatty acids and lowers the serum level ofcholesterol and triacylglycerol. Furthermore the mixture supports thegrowth of bacteria of the genus Bifidobacterium and other beneficialmicroorganisms of the natural intestinal flora. Moreover, it has beenfound that this type of mixture has no laxative effects, even when givenin an amount of 1 g/kg body weight/day.

Due to the above beneficial effects on the gastro-intestinal tract it isalso possible to use the mixture as a pharmaceutical preparation for theimprovement of the intestinal function. Such preparations can be in formof conventional formulations, e.g. as tablets, dragees, capsules and thelike. In case of microorganisms able to utilize the mixture as acarbohydrate source, the mixture can also be used in nutritive media forthe cultivation of such microorganisms.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood, that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BEST MODE FOR CARRYING OUT THE INVENTION

The method according to DK patent application No. 1592/88 and the methodaccording to the present invention as well as the use of mixturesobtained by the inventive method are described in greater detail in thefollowing Examples, where reference Examples are denoted by letters andExamples according to the present invention are denoted by numerals.

EXAMPLE A: PREPARATION OF A SYRUP

The harvested tubers of the Jerusalem artichoke are treated on aconventional plant for treating sugar beets. The treatment includes thefollowing steps.

1. Feeding and removal of stones and grass

The tubers are emptied into a beet yard and flow into the plant, whilestones as well as green plant material (i.e. grass and stem material)are removed. Most of the soil is also washed off.

2. Cutting

For preparing the tubers for the subsequent extraction process saidtubers are cut into cosettes with a cross-section of approx. 0.5×0.5 cm.Their length depends on the size of the tubers (typically 2-5 cm). Thecutting process is performed on a conventional sugar beet cutter. Itcan, however, be necessary to use other knives.

3. Extraction

In order to extract the desired mixture from the cosettes, theextraction process is performed analogous to the one known from theextraction of sugar from sugar beets. The extraction is performed in aso-called DDS-diffusor, a trough with a steam mantle. The trough has asmall inclination and is provided with a twin screw ensuring transportof the cosettes.

The cosettes are extracted according to the counterflow principle, i.e.the cosettes are fed through a funnel in the bottom part of the trough.Water as well as the press juice obtained in step 4 are fed into the toppart of the trough.

The cosettes are then transported counter to the flow of water, wherebyoligosaccharides and other water-soluble components, such as salts andproteins, pass into the water phase.

The temperature during the extraction is between 60°-85° C. Such a hightemperature ensures not only a good solubility of oligosaccharides butalso partially denaturates the protein as to render it insoluble.Enzymes are also denaturated and thus inactivated at this temperature.

The dry matter content of the extract is 10-17% by weight.

4. Pressing of the pulp

The extracted cosettes are pressed in a special press of the type alsoused for conventional sugar beet processing. This is done to increaseboth the yield of oligosaccharides as well as the dry matter content ofthe pulp. The pulp has often to be dried with respect to stabilityduring transport and storage until use, e.g. in form of foodstuffs. Theincrease in yield is achieved by transferring the press juice back tothe extraction process, as described above.

5. Purification of the juice

The juice obtained by the extraction process is turbid since it containsparticulate and colloidal material. Amongst the impurities present arepectin and proteins as well as cell material from the cosettes.

In order to remove these impurities slaked lime, Ca(OH)₂ is added up toa pH-value of 10.5-11.5 thereby precipitating a part of the impurities.

The pH-value is lowered again by adding CO₂ or phosphoric acid eitherbefore or after filtration. Thus excess calcium is precipitated eitheras calcium carbonate or calcium phosphate. The pH-value after thistreatment is between 8.0 and 9.5. The juice is subsequently filtered.The temperature during the lime treatment is 35°-40° C. and during thelowering of the pH-value and the filtering it is 60°-80° C.Precipitation and filtering are improved at the higher temperature.

The purification of the juice is performed using the same equipment asin conventional sugar beet processing.

After the purification the dry matter content is 9-16% by weight.

6. Ion exchange

After the purification the juice still contains salts (3-8% by weight ofthe total dry matter) and it is brownish or greenish in colour. It isthus subjected to a cation as well as an anion exchange.

The cation exchange (e.g. on a "Duolite™"-C20 resin) is performed at atemperature of 25°-35° C. in order to avoid hydrolysis of theoligosaccharides.

During the anion exchange (e.g. on a "Duolite™" A-378 resin) thecoloured compounds of the juice are also removed as to render said juicea colourless oligosaccharide solution. The dry matter content after theion exchange is 8-14% by weight.

7. Treatment with active carbon

It may be necessary to treat the ion-exchanged juice with active carbonin order to remove possible residues of coloured compounds, undesiredtaste or odoriferous compounds.

8. Evaporation

Before the actual evaporation it is advantageous to employhyperfiltration (reverse osmosis) in order to remove part of the waterso that the dry matter content is up to approx. 25% by weight. By thisstep a more gentle treatment is obtained.

The evaporation is performed in a multi-step evaporator such as afalling film evaporator. The juice is evaporated to a syrup of a drymatter content of between 75-85% by weight.

Thereafter the syrup is evaporated in a vertical vacuum evaporation to adry matter content of 91-96% by weight.

EXAMPLE B

Tubers of Jerusalem artichoke are treated as described in Example Aunder the following conditions. The extraction temperature is 70° C. Thedry matter content of the extracted juice is 12% by weight. Ca(OH)₂ isadded at 35° C. to pH 11.5 and the pH value is then lowered to 9 byadding CO₂. Then the juice is filtered at 60° C. After ion exchange at25° C. on "Duolite™" C20 and "Duolite™" A-378 and treatment with activecarbon the juice has a dry matter content of 9% by weight due todilution during ion exchange. The juice is hyperfiltrated to a drymatter content of 25% by weight, and then evaporated first in a fallingfilm evaporator to 85% by weight and then to 92.6% by weight in a thinfilm evaporator (model LUWA, available from Buss-SMS, Kaiserstr. 13-15,D-6308 Butzbach).

EXAMPLES C AND D: PREPARATION OF A MIXTURE IN FORM OF A DRY POWDERMethod 1: "Drying with Quenching" EXAMPLE C

A syrup is used having a dry matter content of 94.3% by weight obtainedaccording to the method of Example A being of a temperature of 90° C.,at which temperature the syrup is liquid.

The syrup, almost representing a melt, is transferred to the outersurface of a cooling drum in form of a thin layer. The temperature onthe surface of the cooling drum is minus 8° C.

The syrup solidifies to form a glass-like mass and does not formcrystals, as conventional sugar solutions do.

The hard, glass-like material is scraped off the cooling drum in form offlakes. These flakes are roughly ground (granulated) 4nd subsequentlydried in a fluid bed dryer at a temperature of below 60° C. to a drymatter content of 96.2% by weight.

The material can subsequently be ground to a desired grain size, such asbelow 250 μm.

Method 2: "Vacuum Flash Drying" EXAMPLE D

A syrup having a dry matter content of 91-93% by weight obtainedaccording to the method of Example A and being of a temperature of80°-100° C. is transferred to a vacuum chamber provided with a conveyorbelt.

By adjusting the dry matter content and the temperature of the feedingmaterial as well as the vacuum in the chamber the obtained mixture has atemperature of 30°-40° C. after evaporation of water and is solid. Theheat of evaporation is derived from the enthalpy of the feedingmaterial, i.e. it is not necessary to add heat during the dryingprocess.

At an absolute pressure of 23.8 or 42.2 mmHg the mixture leaves thevacuum chamber at a temperature of approx. 30° C. or approx. 40° C.respectively.

The process can be described as a flash-like evaporation in vacuum, thefeed being a syrup and the final product a dry powder.

The above process differs from conventional flash evaporation by beingperformed in vacuum, thus rendering it unnecessary to overheat thefeeding material, and by the feeding material being a solution and not awet, particulate matter.

An interesting property of this drying method is the fact that themixture is cooled to a desired final temperature of typically 30°-40° C.during the drying/water evaporation.

EXAMPLE E

Roots of chicory are treated as described in Example A under thefollowing condition. The extraction temperature is 75° C. The dry mattercontent of the extracted juice is 13% by weight. Ca(OH)₂ is added at 35°C. to pH 11.0 and the pH value is then lowered to 9 by adding CO₂. Thenthe juice is filtered at 70° C. After ion exchange at 25° C. on"Duolite™" C20 and "Duolite™" A-378 and treatment with active carbon thejuice has a dry matter content of 9.5% by weight due to dilution duringion exchange. The juice is hyperfiltrated to a dry matter content of 25%by weight, and then evaporated first in a falling film evaporator to 85%by weight and then to 92.3% by weight in a thin film evaporator (modelLUWA, available from Buss-SMS, Kaiserstr. 13-15, D-6308 Butzbach). Theobtained syrup is adjusted to 98° C. and is fed into a vacuum chamberwith free fall. The absolute pressure in the vacuum chamber is 38 mmhg.The dry powder leaving the chamber has a dry matter content of 97% byweight and a temperature of 38.5° C.

EXAMPLE 1 Chromatography

Example A, steps 1-7, is carried out, i.e. including the treatment withactive carbon. The purified juice is transferred to an ion exchangeresin "Duolite™" C 204-Na. Then the inulide mixture is eluted withwater. The dry matter content of the juice as well as of the fractionsof the eluate are determined by refractomy. The sucrose content of thejuice as well as of the fractions of the eluate are determined by theHPLC method where the sample is transferred to a LICHROSORB column (aminform) having a diameter of 7 mm and a length of 25 cm. The eluant is anacetonitrile/water mixture having a volume ratio of 67:33. A RI(refraction index) detector is used. The accumulated amounts appear fromTable 1.

                  TABLE 1                                                         ______________________________________                                                 accumulated dry matter                                                                        accumulated sucrose                                  fraction % by weight of dry                                                                            % by weight of acc.                                  No.      matter in juice dry matter                                           ______________________________________                                        1        3.9             0.0                                                  2        14.3            0.0                                                  3        31.4            0.0                                                  4        50.6            0.8                                                  5        69.9            3.7                                                  6        83.4            9.9                                                  7        92.3            14.9                                                 8        97.7            17.4                                                 9        99.4            19.0                                                 ______________________________________                                    

Fractions 1-5 having a sucrose content of 3.7% by weight of dry matterare combined and evaporated as described in Example A, step 8, whereuponthe mixture is dried as described in Example D.

When analysed the product had the following composition:

    ______________________________________                                        dry matter        96.2%   by weight                                           ash               0.0%    by weight                                           glucose           0.0%    by weight                                           fructose          0.0%    by weight                                           sucrose           3.7%    by weight                                           GF.sub.2          8.3%    by weight                                           GF.sub.3          10.0%   by weight                                           GF.sub.n *        78.0%   by weight                                           ______________________________________                                         *n ≧ 4                                                            

Apart from the result for dry matter, all results are given in % byweight of dry matter.

EXAMPLE 2 NANOFILTRATION

Example A, steps 1-5, is carried out, i.e. including the purification ofthe juice. The purified juice is nanofiltered using a nanofiltrationmembrane HC50 PP available from DDS Filtration, DK-4900 Nakskov, havingan NaCl permeability of 40-60% at 20° C. and 40 bar. The juice isconcentrated twice and diafiltered at 50° C. and 20 bar, the amount ofwater used being 200% by weight of the amount of feed solution.

The results after the nanofiltration are given in Table 2.

                  TABLE 2                                                         ______________________________________                                                               retentate from                                                         juice feed                                                                           nanofiltration                                         ______________________________________                                        dry matter content                                                                              10.5     24                                                 (% by weight)                                                                 ash at 550° C.                                                                           11.4     5.6                                                (% by weight/dry matter)                                                      inulide purity*   85       90                                                 (% by weight/dry matter)                                                      sucrose + glucose +                                                                             20       12                                                 fructose                                                                      (% by weight/dry matter)                                                      ______________________________________                                         *Inulide purity is the content of glucose + fructose + GF.sub.n compared      to the entire dry matter content. Inulide purity is determined by             hydrolysis and subsequent analysis of glucose + fructose.                

As is apparent the content of sucrose, glucose and fructose as well asash is considerably reduced. The reduced ash content is due to the factthat salts and proteins are also removed.

The evaporation of the permeate results in a molasses-like productcontaining

76% by weight dry matter

35% by weight sucrose+glucose+fructose

7% by weight protein, and

44% by weight ash.

This product is suitable for animal food.

The above retentate is treated as described in Example A, starting withstep 6, the volume of the ion exchanger being considerably reduced sincethe salt content has already been considerably reduced. The syrup isthen dried as described in Example D.

When analysed the product had the following composition:

    ______________________________________                                        dry matter        95.4%   by weight                                           ash               0.0%    by weight                                           glucose           0.0%    by weight                                           fructose          0.0%    by weight                                           sucrose           4.3%    by weight                                           GF.sub.2          9.5%    by weight                                           GF.sub.3          11.2%   by weight                                           GF.sub.n *        75.0%   by weight                                           ______________________________________                                         *n ≧ 4                                                            

Apart from the result for dry matter, all results are given in % byweight of dry matter.

EXAMPLE 3 Chromatography

Example A, steps 1-5, is carried out, i.e. including the purification ofthe juice. The purified juice is evaporated up to a dry matter contentof 50% by weight and chromatographed on an ion exchange resin of thetype "Duolite™" C204-Na. The column is eluted with water to obtain afraction having a reduced sucrose content of 7.8% by weight of drymatter. The composition of the feed mixture, the product fraction andthe rest fraction appear from the following Table 3.

                  TABLE 3                                                         ______________________________________                                                     feed    product   rest                                                        mixture fraction  fraction                                       ______________________________________                                        % by weight dry matter/                                                                      100       82        18                                         dry matter content of                                                         feed mixture                                                                  % by weight sucrose/                                                                         16.7      7.8       57.2                                       dry matter                                                                    % by weight ash/                                                                             11.4      11.4      11.4                                       dry matter                                                                    ______________________________________                                    

The product fraction is treated in accordance with remaining steps ofExample A, i.e. steps 6-8, and dried according to Example D. Theresulting product has a sucrose content of 8.8% by weight of dry matterand further contains 0% ash.

The rest fraction can be treated as above and incorporated in human oranimal foodstuffs and beverages. Subsequent to evaporation the sucrosecontent of the rest fraction is 64.6% by weight of dry matter andfurther contains 0% ash.

EXAMPLE 4 Chromatography Followed by Nanofiltration

The product fraction and the rest fraction of Example 3 are subjected tonanofiltration as described in Example 2.

The composition of the product fraction before and after nanofiltrationat 50° C. and 15 bar is as follows:

                  TABLE 4                                                         ______________________________________                                                      product fraction                                                                         retentate of                                                       of Example 3                                                                             nanofiltration                                       ______________________________________                                        % by weight dry matter                                                                        20           24                                               % by weight ash/                                                                              11.4         5.6                                              dry matter                                                                    inulide purity  85           90                                               (% by weight/dry matter)                                                      sucrose + glucose +                                                                           7.8          3                                                fructose (% by weight/                                                        dry matter)                                                                   ______________________________________                                    

As is apparent a further reduction of sucrose+glucose+fructose isobtained when using chromatography followed by nanofiltration.

Subjecting the rest fraction to nanofiltration at 60° C. and 40 bar, thecomposition of the resulting product is as follows:

                  TABLE 5                                                         ______________________________________                                                      rest fraction                                                                          retentate of                                                         of Example 3                                                                           nanofiltration                                         ______________________________________                                        % by weight dry matter                                                                        12         24                                                 % by weight ash/                                                                              11.4       5.5                                                dry matter                                                                    inulide purity  85         90                                                 (% by weight/dry matter)                                                      sucrose + glucose +                                                                           57.2       55                                                 fructose (% by weight/                                                        dry matter)                                                                   ______________________________________                                    

EXAMPLE 5 Nanofiltration Followed by Chromatography

The retentate of Example 2 is subjected to chromatography as describedin Example 1. The result is as follows:

                  TABLE 6                                                         ______________________________________                                                     feed    product   rest                                                        mixture fraction  fraction                                       ______________________________________                                        % by weight dry matter/                                                                      100       92        8                                          dry matter content of                                                         feed                                                                          % by weight sucrose/                                                                         12        8.5       52.3                                       dry matter                                                                    % by weight ash/                                                                             6.2       6.2       6.2                                        dry matter                                                                    ______________________________________                                    

The product fraction is treated in accordance with the remaining stepsof Example A, and dried according to Example D. The resulting producthas a sucrose content of 9.4% by weight of dry matter and furthercontains 0% ash. Thus subjecting a nanofiltered juice to chromatographyresults in a product fraction comprising 92% of the dry matter in thejuice. The dry matter content of the product fraction obtained bychromatography of the non-nanofiltered juice is, on the other hand,69.9%. The yield after nanofiltration is 86% by weight of the dry matterof the juice. The combination of nanofiltration and chromatographyresults thus in an increased yield of 92%×86%=79.1% compared to theabove 69.9% obtained by chromatography alone.

Subsequent to evaporation and drying the rest fraction has a sucrosecontent of 58.1% by weight of dry matter and contains 0% ash. Theevaporated and dried rest fraction is suitable to be incorporated inhuman and animal foodstuffs and beverages.

EXAMPLE 6

The mixtures prepared as described in Example C and 1 as well as thecommercially available products "Neosugar"-syrup and "Neosugar"-powderhave, according to an analysis, the following composition, cf. Table 7.All analysis results of the carbohydrates are given in relation to thedry matter content. All values in Table 7 are in % by weight.

                  TABLE 7                                                         ______________________________________                                        "Neosugar-"    "Neosugar"  mixture  mixture                                   syrup          powder      Ex. C    Ex. 1                                     ______________________________________                                        dry matter                                                                            79.0       96.4        96.2   96.2                                    ash     0          0           0      0                                       glucose 29.5       1.1         1.3    0                                       fructose                                                                              1.7        0.8         1.9    0                                       sucrose 10.6       2.8         15.8   3.7                                     GF.sub.2                                                                              28.0       36.4        12.9   8.3                                     GF.sub.3                                                                              30.2       58.9        11.1   10.0                                    GF.sub.n *                                                                            0          0           57.0   78.0                                    ______________________________________                                         *n ≧ 4                                                            

On the basis of the experimental results with respect to "Neosugar"described in an article of T. Tokunaga et al., J. Nutr. Sci. Vitaminol.,32, 111-121, 1986, it is evident, that the laxative effect of thecompounds of the general formula GF_(n), where n>2, is more extensive ata lower molecular weight.

It has thus to be assumed that the mixture according to Example C isless laxative than "Neosugar".

The most laxative component is presumably GF₂. The content of thiscomponent in "Neosugar" is 28.0% and 36.4% respectively and there is10.8% in the mixture of Example C. In the mixture according to Example 1the content has been further reduced to 8.3%.

EXAMPLE 7 Chewing Gum

The sugar content in a conventional chewing gum was replaced by acombination of the mixture prepared according to Example 1 andaspartame. It was found that this chewing gum possessed betterorganoleptic properties, especially with regard to "mouthfeel" ortexture and rest volume, i.e. the volume left after chewing of a chewinggum for a predetermined period of time, than corresponding chewing gumscomprising sucrose.

EXAMPLE 8 Sweets

Sweets with the following basic formulation, wherein 67% of the sucrosewere replaced by the mixture of Example 5, were prepared.

Basic formulation:

100 g sucrose

200 g mixture of Example 5

120 g glucose

100 g water

The basic formulation was boiled down while heating to 170° C.

The basic formulation was subsequently cooled and flavourings were addedjust before the formulation could no longer be kneaded. Amongst theflavourings used were peppermint oil, aniseed oil, eucalyptus oil orothers.

After the kneading in of the flavourings the resulting formulation wascut into the desired form and left to stiffen.

The sweets prepared according to this method were less sweet and had alower calorie content than conventional sweets.

EXAMPLE 9 Cake Formulation

In this formulation 35% of the sucrose content were replaced by themixture of Example 2. The following recipy was used:

    ______________________________________                                                    regular cake   formulation with                                               formulation    mixture of Ex. 2                                   ______________________________________                                        margarine     250     g        250    g                                       flour         250     g        250    g                                       sugar (sucrose)                                                                             200     g        130    g                                       mixture of Example 2                                                                        --               70     g                                       eggs          6                6                                              ______________________________________                                    

The cakes were both baked for 1.25 h at 150° C. in a circulating airoven. The results were as follows. There was no difference during thepreparation of the dough. The cake formulated with the mixture ofExample 2 was less sweet, but apart from that both cakes tasted alike.

EXAMPLE 10 Chocolate

    ______________________________________                                                      regular formulation with                                                      formulation                                                                           mixture of Ex. 4                                        ______________________________________                                        cocoa mass      39.4%     39.4%                                               cocoa butter    2.0%      2.0%                                                vegetable fat   3.0%      3.0%                                                milk powder (25% fat)                                                                         3.0%      3.0%                                                butter fat      3.0%      3.0%                                                lecithin        0.57%     0.57%                                               vanillin        0.01%     0.01%                                               sodium saccharide                                                                             --        0.02%                                               mixture of Example 4                                                                          --        49.0%                                               sucrose         49.02%    --                                                  ______________________________________                                    

The only difference between the two chocolates is the lower caloriecontent of the inulide-containing chocolate and the two chocolates havethe same sweetness.

EXAMPLE 11 Chocolate

In the chocolate formulation of Example 10 the mixture of Example 4 wassubstituted by a mixture prepared from roots of chicory according toExample E combined with Example 3. The resulting chocolate had the samesweetness and the same low calorie content as the inulide-containingchocolate of Example 10.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

We claim:
 1. A method for preparing a mixture of fructose, glucose andcompounds of the general formula GF_(n), wherein G is glucose and F isfructose and n is an integer, comprising calculated as dry matter0-10%by weight of G+F+GF, 5-20% by weight of GF₂, 5-15% by weight of GF₃,5-15% by weight of GF₄, 5-15% by weight of GF₅, and 80-25% by weight ofGF₆ and above,where the mixture is recovered from tubers of Jerusalemartichoke (Helianthus tuberosus L.) or from roots of chicory(Cichorium), by means of a method which does not involve any chemicalmodification of the components of the mixture, by which method thefollowing steps are carried out: a) the substantially cleaned tubers orroots are cut into cosettes, b) the cosettes are subjected to extractionwith water, c) the extract, or juice, is treated in a suitable order oneor more times by each of the following steps:1) addition of Ca(OH)₂, toa pH value of 10.5-11.5, 2) addition of CO₂ or phosphoric acid, to a pHvalue of 8.0-9.5 and 3) filtration d ) the juice from step c) issubjected to ion exchange, e ) the juice from step d) is optionallytreated with active carbon, f) the juice from step d) or e) isoptionally concentrated by hyperfiltration, g) the juice from step d) ,e) or f) is optionally evaporated to a syrup, and h) the syrup isoptionally dryed to a powder, characterized by subjecting the juice orsyrup during any suitable moment subsequent to step c) but prior to steph) to a physical separation to reduce the amount of fructose, glucoseand sucrose, said physical separation being carried out bychromatography or nanofiltration or both.
 2. A method as claimed inclaim 1, characterized by preparing the mixture in form of a juice orsyrup or a dry powder.
 3. A method as claimed in claim 1, characterizedby the physical separation being carried out by chromatography.
 4. Amethod as claimed in claim 3, characterized by the juice or syrup beingsubjected to chromatography by using an ion exchange resin and water aseluant, and by subsequently treating the eluted fractions having a lowsucrose content in accordance with any subsequent step.
 5. A method asclaimed in claim 1, characterized by the physical separation beingcarried out by nanofiltration.
 6. A method as claimed in claim 5,characterized by the juice or syrup being nanofiltered and the retentatebeing treated by one or more steps selected from the group consisting ofextraction, ion exchange, treatment with active carbon, concentration byhyperfiltration, evaporation, and drying.
 7. A mixture comprisingcalculated as dry matter- 10% by weight of G+F+GF, 5-20% by weight ofGF₂, 5-15% by weight of GF₃, 5-15% by weight of GF₄, 5-15% by weight ofGF₅, and 80-25% by weight of GF₆ and above,produced in accordance withthe method of claim
 1. 8. A foodstuff or beverage for animals or humanbeings prepared by incorporating in a foodstuff or beverage the mixtureaccording to any of the preceeding claims.